Each reserve officer of the Army, Navy, Air Force, or Marine Corps who is in an active status or on an inactive-status list and who reaches the maximum age specified in section 14509, 14510, 14511, or 14512 of this title for the officer’s grade or position shall (unless the officer is sooner separated or the officer’s separation is deferred or the officer is continued in an active status under another provision of law) not later than the last day of the month in which the officer reaches that maximum age—